Stifle Lameness in the Horse

Stifle Lameness in the horse Stifle problems are a relatively infrequent cause of lameness in horses. An increasing number of conditions affecting this region are, however, being recognised and being diagnosed more accurately with advances in imaging technology. Acute stifle lameness often results from direct trauma or is associated with exercise where abnormal rotation forces may act on the joint. Clinical signs vary from horse to horse. The degree of lameness is variable from very mild to very severe non-weight bearing depending on which structure or structures are affected. Muscle wastage may or may not be present at the time of the examination; when present it Fig 1. radiograph of normally is an indication of a long term problem. Swelling subchondral bone cyst on inside of the femur of the soft tissues around the stifle region or distension of the joints can be subtle or obvious. A meticulous and systematic lameness examination needs to be carried out to identify the source of lameness. Both static and dynamic evaluations of the horse at walk and trot in a straight line in a hard surface and in a soft and hard surface in the circle are necessary to assess the degree of lameness. Nerve blocks are necessary when there are no obvious indications that the lameness is localized to the stifle Fig 2. Arthroscopy view of the same bone cyst. The metal region. Joint anaesthesia (‘joint block’) is normally used to probe is exploring the depth localize the lameness specifically to the stifle. The stifle of the defect joint is the largest, most complex joint in the horse and is divided in 3 compartments, the femoro-patellar joint, the lateral femoro-tibial joint, and the medial femoro-tibial joint. Mild to moderate improvement in lameness after a joint block is an indication of a stifle problem, however some acute injuries do not respond to joint blocks. After localization of the lameness or when a problem is suspected in this area, radiography is often the first diagnostic technique used. Radiographs are a useful tool to identify osseous problems such as osteochondral lesions, Fig 3: Intra-operative view of a cranial cruciate ligament tear before and after cleaning up with a motorized tool which removes frayed tissue and so minimises the likelihood of severe arthritis. subchondral bone cyst or fractures, but the sensitivity to detect soft tissue injuries and cartilage lesions is poor. Ultrasonography is the only non-invasive technique to evaluate the soft tissue structures of the stifle. Nuclear scintigraphy (‘bone scans’) can be useful in some cases. Surgical arthroscopy, i.e keyhole surgery, has become an essential tool in the diagnostic evaluation and treatment of stifle joint disease, just like in human knee injuries. Injuries such as cartilage lesions, cruciate ligament tears or meniscal damage are difficult to appreciate with other diagnostic modalities. Arthroscopy of the stifle joint is necessary to assess the extent of soft tissue injuries allowing a more accurate prognosis and maximising the formulation of treatment plans. Some horses with even very extensive cartilage damage may return to athletic function after arthroscopic debridement and lavage. A more pessimistic prognosis may be given to older horses, those with more severe pre-operative lameness, and those with severe radiographic changes or arthroscopic findings such as large meniscal tears. Facebook.com/DickVetEquine 4 @DickVetEquine SPRING 2014 The Dick Vet Equine Practice Sarcoids by Jenny Clements What is a Sarcoid? Sarcoids are the most common skin tumour affecting horses worldwide. They vary greatly in size, appearance, location and response to treatment. They are confined to the skin and do not spread to the internal organs but nonetheless, can be a challenge for owners and veterinary surgeons. The cause of sarcoids is still not fully understood but the bovine papillomavirus is widely accepted as being significant. There is also evidence that flies play an important role in the pathogenesis. Sarcoid facts • Sarcoids are common. • Sarcoids are a type of skin tumour. • Once a sarcoid horse, always a sarcoid horse – a horse with a sarcoid is liable to develop more. • Sarcoids can develop anywhere on the skin but commonly affect the chest, groin, sheath and eyes. • Trauma to a sarcoid may aggravate it. • No two sarcoids are the same, each needs to be assessed on an individual basis. • Treatment is not always necessary but if required, can be difficult and expensive and is not always successful. • Sarcoids may recur, despite treatment. Fig 2. Verrucose Fig 5. Malevolent Nodular Mixed Nodular sarcoids are firm round lumps that appear anywhere on the horse’s body but commonly in the axilla (armpit), thigh, groin, sheath and eyelid. They are normally covered by skin and can be freely mobile underneath it or firmly adhered to it. In some cases, the overlying skin can be ulcerated. A mixed sarcoid is one that contains two or more of the sarcoid types. DIAGNOSIS The diagnosis of a sarcoid can usually be made on clinical appearance alone. For some forms of therapy, photos are taken and submitted to Liverpool University via their sarcoid submission website, who then recommends a suitable treatment protocol. Biopsies are rarely indicated in the diagnosis of sarcoids as surgical aggravation can turn a simple type into a more aggressive form. However, they are performed occasionally on sarcoids with an atypical appearance but we need to be prepared to treat these cases promptly if a diagnosis is subsequently made. Types of sarcoid Fig 3. Nodular TREATMENT There are 6 distinct clinical entities, namely; occult, verrucose (warty), nodular, fibroblastic, malevolent and mixed sarcoids. Fibroblastic There are many reported treatments for sarcoids which in itself clearly demonstrates that no one treatment will be effective in each and every case. Each sarcoid should be assessed on an individual basis, by a veterinary surgeon. Inappropriate treatment can rapidly convert a simple sarcoid into an aggressive one. Treatment options include: Occult Lesions are hairless, often circular and easily mistaken for ringworm lesions or rubs from tack. They are seen on the relatively hairless areas such as the face, neck, chest and groin. Fibroblastic sarcoids have a characteristic fleshy, aggressive and ulcerated appearance. They are commonly found in the axilla, groin, sheath, eyelid and lower limb. They may easily bleed and can look like “proud flesh”. Indeed, they can occur at sites where there has previously been a wound (especially if there are sarcoids elsewhere on the horse) or develop rapidly from occult, verrucose or nodular sarcoids which have been traumatised. Watch and Wait Occasionally a decision is made to monitor a sarcoid, rather than treat it. This is generally done on lesions which are small and have remained static for some time. An advantage is that the cost of treatment can potentially be avoided but consideration must be given to the possibility of spread of the sarcoid elsewhere on the horse or to other horses. AW4-LUDES cream Fig 4. Fibroblastic Fig 1. Occult Malevolent Verrucose Verrucose sarcoids have a “wart-like” appearance, are often grey in colour and may have a cracked or flakey appearance. 2 www.DickVetEquine.com 0131 650 6253 The malevolent sarcoid is the most aggressive form of sarcoid. Its appearance is of multiple, invasive sarcoids, generally consisting of nodular and fibroblastic types. Although, malevolent sarcoids do not invade internal organs, they can be too aggressive to treat successfully. Fortunately, this type of sarcoid is rare. SPRING 2014 This is our most commonly used sarcoid treatment and is also known as the “Liverpool sarcoid cream”. It is a topical chemotherapy treatment that contains 5-fluorouracil, heavy metals, cytotoxic chemicals and natural plant oils. To obtain a prescription for this cream, photos need to be submitted through the Liverpool sarcoid submission website. We complete a questionnaire and upload photos of your horse’s sarcoids through this website. Liverpool charge a consultation fee (currently £20.74 + VAT) to examine the photos and issue a prescription. We automatically add this fee to your account at this stage. Once the prescription is issued, we contact you to advise you of the protocol and ask you to communicate directly with SPRING 2014 Liverpool to pay for the cream. The cost of the cream varies because Liverpool will sometimes prescribe a treatment course using more than one strength of cream. Once the cream is purchased, it will be dispatched to us and we will then ring you to book in dates for application. Only veterinary surgeons are permitted to apply the cream, due to its caustic nature. It is likely that 4-5 applications will be recommended at intervals of 24-72 hours. We usually suggest that we re-examine the horse or photos of the lesions at approximately 6 weeks post treatment. At this time, the treated area often looks like a hard plaque of dead tissue that will eventually drop off. We normally re-submit photos at this stage (no consultation fee is incurred for follow-up photos). Liverpool advise us how to proceed and whether repeated courses of treatment are necessary. It is worth noting that the submission procedure can take a little time and that the process is not an insignificant expense when you consider there are fees for the initial examination, Liverpool consultation, cream and applications. However, visit fees can be saved if you wish to bring your horse to the practice for each treatment. Additionally, some horses become quite sore during the treatment course and require sedation for the cream to be applied safely and anti-inflammatories to reduce the swelling and pain. Surgery Surgical options include sharp surgical excision, cryosurgery (freezing) and laser surgery. Surgery is only successful if the sarcoid is well defined and confined because you need a wide healthy margin to prevent recurrence. If this is not achieved, you can get rapid development of a fibroblastic sarcoid at the surgery site. Therefore, surgical options are rarely our first choice of treatment. Ligation Application of a ligature or band to a sarcoid with a well-defined “neck” can be very successful. This method is sometimes combined with application of the AW4-LUDES cream at the base to ensure complete removal of the sarcoid. BCG Injection Injection of BCG (used for human TB vaccination) works well for treatment of nodular sarcoids around the eye. It works less well at other locations. As you can see, treatment of sarcoids is not always easy. If you would like to discuss sarcoids further, please do not hesitate to contact the practice on 0131 650 6253. 0131 650 6253 www.DickVetEquine.com 3